This invention relates to a method of establishing a detection map for a network of sensors. When designing a network of sensors to establish an area of detection with a corresponding detection map, it is common to lay out an initial pattern of sensors that employs the theoretically expected detection capability of the sensor network based upon the expected detection zones of the individual sensors and then selects initial locations for the individual sensors such that their expected detection zones overlap in such a way as to provide an expected detection map corresponding to a detection perimeter. However, in real-world applications, the actual detection zone of a sensor can be significantly altered by the terrain in which it is placed. Numerous factors are included in the concept of terrain for the purposes of this invention. These include but are not restricted to man-made structures, topography, flora, ground composition including characteristics such as soil type, degree of compaction, ground moisture, and lithic components, and other factors that might alter the value of a measured parameter for a particular sensor. For example, for seismic sensors, the ground composition such as the type of soil, the degree of compaction, the presence of buried rocks, and even the moisture content of the ground can affect the sensor range and sensitivity. The presence of trenches or drop-offs can also change the sensor range. For another example, the wind level or the presence of intervening objects such as plants, rocks, and man-made structures can affect the range and sensitivity of acoustic sensors. For another example, an optical sensor may have an obstructed line of sight or the local topography may include inclines that alter the pointing angle of the sensor.
In addition, it may not be possible to place the sensor on the initially selected location due to the presence of interfering objects, such as plants, boulders, trenches, drop-offs, water features, man-made structures, and numerous other aspects of the real terrain that inhibit placement of the sensor in a previously selected location. The forced relocation of the sensor to accommodate the terrain may result in a degradation of the quality of overlap of the detection zones of the various sensor units comprising the sensor network and result in failure to establish an effective detection perimeter. In such cases, the expected detection map and the actual detection map can differ, markedly, leading one to assume an adequate detection perimeter has been established when, in reality, it has not.
Thus, there is a need for a method to establish the actual detection map of a real network of sensors that takes into account the actual detection zone of each sensor in the actual location where it has been placed. It is also desirable to know in real-time while the sensor network is being laid out whether the network of sensors is providing the desired overlap of detection zones to produce the desired detection map and to identify alternative locations for the sensor units when the initial pattern of sensors does not provide the desired level of coverage.